Biomedical subjects
Publications and source records attributed to A G Hunter.
A fetal thigh muscle biopsy was performed at 18 weeks and 6 days' gestation using an automatic 18-gauge biopsy needle. A positive immunoreaction with antisera to the amino- and carboxy-terminals of dystrophin excluded Duchenne muscular dystrophy from this at-risk male.
Single copies of tiny chromosome fragments, appearing either as single or as double minutes, were observed in a high frequency in amniotic fluid cultures of five mothers who underwent prenatal testing because of advanced age. In four cases, the minutes had arisen de novo. The minutes were later confirmed in fetal skin following termination of pregnancy in one case; in another, in cord blood following the birth of a normal boy; and in the third, in peripheral blood of a normal 3-year-old girl. In the fourth case, the minutes were not confirmed in cord blood following the birth of a normal boy. A follow-up chromosome study of the baby boy in the fifth case was not possible but the minutes were maternally transmitted.
OBJECTIVE: This report examined associations between family structure and 393 fourth-grade children's aggressive behavior. METHOD: In an epidemiologically defined urban community population, both teacher and parent ratings of child aggressive behavior were examined among family structures that reflected current demographics. Relative risks for teacher- and parent-rated child aggressive behavior in mother-alone households were compared with those in the next most prevalent family structures (mother-father, mother-grandmother, and mother-male partner families). RESULTS: With all income groups combined, teachers rated boys and girls in mother-alone families as more aggressive relative to mother-father families. Among low-income families, the protective effects for mother-father families were not apparent, and mother-male partner families were associated with an increased risk for teacher-rated aggression for boys. CONCLUSION: Absence of and type of second adult present, child gender, home and school context, and income were important factors that moderated the associations between family structure and child aggressive behavior in this urban setting.
We report on a stillborn male infant with a mosaic ring 13 karyotype (45,XY,-13/46,XY,-13,+r(13)) with apparent aprosencephaly and clinical findings similar to those reported previously in the XK-aprosencephaly syndrome. Findings of patients with r(13) are often similar to those seen in individuals with del(13q). This case was unusual because of the presence of aprosencephaly, although brain malformations such as arhinencephaly and cerebellar hypoplasia are present in at least one-half of reported patients with 13q-. The overlap between these syndromes suggests a possible chromosomal model of the XK-aprosencephaly syndrome.
The rate of spontaneous and mitomycin C induced chromosome breakage and sister chromatid exchange (SCE) was studied in three related cases diagnosed with VACTERL-H syndrome. There have been recent reports of sporadic patients with VACTERL-H in whom high rates of chromosome breakage were observed. This has led to the suggestion that some of these patients may represent the severe expression of Fanconi anemia. The pattern of inheritance in our family is highly suggestive of X-linked recessive inheritance supporting the hypothesis that VACTERL-H is, at least in some cases, a syndrome and not an association.
A balanced complex chromosome rearrangement (BCCR) involving 3 chromosomes with 4 breakpoints, was identified in a 36-yr-old woman who was studied because her fetus was discovered to have an unbalanced reciprocal translocation (7q;10q). Analysis of high resolution bands and the application of fluorescence in situ hybridization has identified the BCCR as der(7)t(7;10)(q21.13;q23.33)ins(21;7)(q21.3;q11.22q21.13), der(10)t(7;10)(q21.13; q23.33), der(21)ins(21;7)(q21.3;q11.22q21.13). Alternate segregation of the BCCR appears to be favoured, and has resulted in two pregnancies with an unbalanced chromosome constitution.
Myotonic dystrophy (DM) is an autosomal-dominant disorder that affects 1 in 8000 individuals. Amplification of an unstable trinucleotide CTG repeat, located within the 3' untranslated region of a gene, correlates with a more severe DM phenotype. In three cases, the number of CTG repeats was reduced during the transmission of the DM allele; in one of these cases, the number was reduced to within the normal range and correlated at least with a delay in the onset of clinical signs of DM. Haplotype data of six polymorphic markers in the DM gene region indicate that, in this latter case, two stretches of the affected chromosome had been exchanged with that region of the wild-type chromosome.
Recently an unstable trinucleotide CTG repeat, located within the 3' untranslated region of a gene on 19q13.3 was discovered in kindreds with myotonic dystrophy (DM). The age-of-onset/severity of DM shows a good correlation with CTG repeat size, and pedigrees and data reported to date have shown a striking trend toward amplification of the size of the CTG repeat during transmission from parent to child. The amplification has been accepted as the biological explanation for anticipation in the clinical severity observed in many families with DM. In this paper we report on 3 families where CTG amplification decreased during transmission from parent to child. In one case there was a gene conversion event, while in the remaining 2 there was a simpler reduction in the size of the repeat length. The changes appear to have been accompanied by a reduction in clinical severity in the child when compared to the parent. These observations are discussed in terms of their clinical implications and the biases that may exist in much of the reported data.
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To investigate its inhibitory properties, bovine follicular fluid was collected at different stages of the estrous cycle from small, medium, and large follicles. Follicular fluids were incubated with germinal vesicle stage, bovine oocytes aspirated from small follicles. Nuclear maturation was determined at 24 h. Bovine follicular fluid inhibited the spontaneous maturation of bovine oocytes. The inhibition was reversed when follicular fluid was removed from oocyte cultures by 24 h. Follicular fluid varied in its ability to inhibit germinal vesicle breakdown according to follicle size and estrual stage. Follicular fluid from both small and medium follicles at estrus had the greatest ability to prevent germinal vesicle breakdown but became less potent postestrus. Follicular fluid from large follicles at estrus had less ability to inhibit germinal vesicle breakdown than fluid from small and medium follicles. Strong germinal vesicle breakdown inhibiting activity was present in large, probably atretic follicles at late metestrus, early diestrus, and mid diestrus. However, follicular fluid from large follicles had less germinal vesicle breakdown inhibiting activity at proestrus than follicular fluid from large follicles at late metestrus, early diestrus, and mid diestrus. This proestrual activity was similar to that in Graafian follicles at estrus.
Bovine germinal vesicle oocytes were collected from 2- to 4-mm follicles. Oocytes were matured in medium 199 containing 10% bovine follicular fluid, FSH, and estradiol. Matured oocytes were cocultured for 2 to 24 h with dead bovine sperm in either Tyrode's medium without albumin or with 40% follicular fluid. After removal of sperm, oocytes were cultured an additional 48 to 72 h in synthetic oviduct fluid or medium 199 containing 10% follicular fluid without hormones. Oocyte activation rates (pronucleus to 8 cells), after exposure to dead sperm for 2, 4, 6, 12, or 24 h, in protein-free Tyrode's medium before embryo culture in synthetic oviductal fluid were 11, 17, 41, and 41%. Activation rates were decreased to 3, 9, 8, 27, and 34% for these same times by the addition of estrual follicular fluid to the protein-free Tyrode's medium. Substitution of bovine serum albumin for follicular fluid in the Tyrode's medium resulted in 47% oocyte activation. Activation depended on time and composition of media, occurred with high frequency with matured bovine oocytes under common in vitro culture conditions, and decreased in the presence of bovine follicular fluid. Therefore, because cleavage is not a sufficient measure of embryo quality, parthenogenetic controls must be run.
Renal tubular dysgenesis is a recently recognized autosomal recessive condition characterized by short and poorly developed proximal convoluted tubules, leading to oligohydramnios, Potter sequence, and neonatal respiratory failure. We report an additional 9 cases from one pediatric center, suggesting that this syndrome is not as rare as was previously thought. Normal amniotic fluid volumes in affected pregnancies prior to the 22nd week of gestation have been documented, compromising early prenatal diagnosis. Late second trimester sonographic demonstration of oligohydramnios, with structurally normal kidneys, should suggest this diagnosis and the need for detailed post-mortem pathological examination.
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Bovine sperm acquire the ability to penetrate zona-free hamster oocytes (capacitation) after incubation in TEST-yolk buffer. Our objective was to determine whether such sperm could penetrate zona-intact bovine oocytes in vitro. Bovine cumulus enclosed oocytes from 2- to 5-mm follicles were incubated in maturation medium for 24 h at 37 degrees C. Ejaculated bovine semen was diluted 1: 10 in TEST-yolk buffer, cooled to 4 degrees C, and stored for 8 h to induce capacitation. Sperm were then washed thrice in pH 7.6, .15 M NaCl containing .1% bovine serum albumin V (37 degrees C) and diluted to 2 x 10(6) sperm/ml in fertilization medium. Droplets of fertilization medium containing capacitated sperm, killed sperm, or no sperm were made under paraffin oil. Oocytes (matured 24 h) were added and cocultured with sperm for 8 h and then transferred to fresh fertilization medium for 40 h. After 24 h, 53% of the oocytes had matured (metaphase II). The fertilization rate of the metaphase II oocytes (203) with TEST-yolk capacitated sperm was 87%, whereas the parthenogenetic controls were 2 and 0%, respectively. Therefore, TEST-yolk buffer can be used to capacitate bull sperm for in vitro fertilization.
In order to investigate whether Ig molecules affect bovine fertility, bovine follicular oocytes were tested for an oolemmal receptor that recognized IgG. The zona pellucida was removed from 296 oocytes. The zona-free oocytes were then incubated with purified bovine IgG. its Fc fragment, or its Fab fragment. They were subsequently washed and incubated with the appropriate rabbit antibovine IgG (whole IgG-specific, Fc-specific, or Fab-specific), which was covalently attached to polyacrylamide beads (immunobeads). Bead attachment was scored using light microscopy. Bovine IgG and bovine IgG-Fc bound to the oocytes, whereas the IgG-Fab exhibited negligible binding. The data indicate that a bovine oolemmal receptor exists that binds IgG by recognizing the molecule in the region of the Fc-Fab junction. Thus, the binding of IgG or other Ig molecules to bovine oocytes may play a role in sperm and egg interaction.
Ivemark et al. first described sibs with renal-hepatic-pancreatic dysplasia (RHPD) (Ivemark BI, Oldfelt V, Zetterström R (1959): Acta Pediatr Scand 48: 1-11). Subsequent reports of affected individuals have described additional malformations and syndromes associated with RHPD. In this paper we describe 2 sibs with RHPD in association with Dandy-Walker cyst (DW). Through an examination of the pattern of associated malformations seen in RHPD we argue that RHPD-DW is a distinct monogenetic syndrome, and not an association.
Recent outbreaks of bovine babesiosis caused by Babesia bovis in Swaziland had indicated the presence of the vector tick Boophilus microplus in the country although it had never before been directly identified. Engorged female Boophilus ticks were collected from cattle at diptanks in the course of a tick resistance survey and used to map the distribution of the two different species of Boophilus. B. decoloratus was found to be widespread throughout the country. B. microplus was identified for the first time in Swaziland and was found to have a patchy distribution. The implications of these findings are discussed.
We report a patient whose clinical, radiologic and histopathologic findings are compatible with severe atelosteogenesis (AT-I). The patient is compared with previously reported cases of AT-I, as well as with patients reported as having "boomerang" dysplasia. We conclude that it is reasonable to consider AT-I and boomerang dysplasia as part of a spectrum, probably reflecting a common etiology. More and detailed clinical, radiologic and histopathologic reports are needed to further clarify the relationship of AT-II and AT-III in this family of skeletal dysplasias.